Automatic air-brake



(No Model.)

WQKBYWOOD.. AUTOMATIC AIR BRAKE.

Patented July 4 UNITED STATES PATENT Erica.

VILLIAM KEYVOOD, OF TACOMA, VASl-IINGTON.

AUTOMATIC AIR-BRAKE.

SPECIFICATION forming part. of Letters Patent No. 500,910, dated July 4, 1893.

Application niet August 4, 1892.

To all whom it may concern.-

Beit known that I, WILLIAM KEYwooD, a citizen of the United States, residing at Tacoma, in the county of Pierce and State of Washington, have invented certain new and useful Improvements in Automatic Air- Y Brakes, of which the following specication,

taken in connection with the accompanying drawings, is a full, clear, and exact description, such as will enable those skilled in the art to make and use the same.

My invention relates particularly and is herein shown applied, to that style of brake known as the Vestinghouse automatic brake; and my invention has for its object to avoid a very serious objection to this style of brake as now commonly manufactured, and consists in novel features of construction hereinafter described and claimed.

In the accompanying drawingszv-'Figure l is a sectional view ot' a brake mechanism embodying myinvention. Fig. 2 is an enlarged sectional detail view. Fig. 3 is a sectional view taken on the line 3-3 of Fig. 2.

A represents the triple-valve mechanism, B the auxiliary reservoir connected to one port of said valve by a pipe b; C is the train-pipe connected to another port of said valve by the branch pipe c; and D is the brake cylinder connected with the third port of the triple valve, and also connected with the auxiliary reservoir in the manner now to be explained.

E is a tube extending from the third port of the triple valve and provided with a cap e for closing its upper end.

H is a valve casing provided at one end with an enlarged opening in which is formed a seat h for the valve I, and a contracted bore or opening h extending from said enlarged opening in which is supported the winged extension i of the valve.

K is a branch tube or pipe tapping the tube E nearits top and also tapping the valve casing H below the contracted opening h and extending into an intermediate chamber 71.3. At the opposite lower end of the valve casing H is formed an enlarged opening h2 in which operates a controlling piston L provided with a rod Z, which passes through a contracted central bore Z', of said casing and is adapted to come in contact with the extension t' of the Serial No. 442,171. (No modela) valve I and raise the valve from its seat at the proper time.

M is a spiral spring surrounding the rod Z and impinging at one end against the inner end of the piston L, and at its opposite end against an internal shoulder on the valve casing for holding the piston and rod normally in their outer inoperative position. Thelower end of the valve casing H is connected with the auxiliary reservoir at b by means of the branch pipe N which is secured therein and supports the piston L; and the upper end of the valve casing is connected to the brake cylinder by means of the branch pipe O, as clearly shown in the drawings.

The operation of the device is as follows The auxiliary reservoir being stored in readiness for applying the brakes, the air pressure is reduced in the train-pipe, which shifts the triple valve and allows the air to pass from the auxiliary reservoir into the brake cylinder and apply the brakes in a manner well understood. It is next desired to restore the pressure of the auxiliary reservoir without releasing the brakes. This is done by restoring the pressure in the train-pipe, which shifts the triple valve and opens connection between the train-pipe and auxiliary reservoir and between the valve casing H and exhaust of the triple valve. Now as ordinarily construct-ed the air in the brake cylinder would immediately pass off through the exhaust and allow the brakes to be released.V But in my improved arrangement, the check valve I ob` structs the passage back from the brake cylinder and holds the brakes in applied posi tion until the auxiliary reservoir has been recharged to the proper pressure. When the air in the auxiliary reservoir reaches the proper pressure, the piston L will be raised thereby against the pressure of the spiral spring M, which will cause the rod Z to raise the valve I from its seat and allow the air from the brake cylinder to escape and the brakes to be released, for the spiral` spring M is so tensioned as to allow the piston to be pushed in and raise the valve I from its seat IOO Having` thus fully described the nature of my invention, the following is what I claim as new therein and desire to secure by Letters Patent:

rlhe combination, with the brake cylinder and the pipe connected therewith, the auxiliary reservoir and the pipe connected therewith, and the triple-valve; of the casing located between the pipes, formed With an enlarged opening at one end, providing a valveseat, an enlarged opening' at the other end providing a piston-chamber, an intermediate chamber, a contracted bore beneath the Valveseat and a contracted bore above the pistoncliamber, the check-Valve, exposed to brake cylinder pressure, having a Winged extension, a piston, exposed to auxiliary reservoir pressure, having a rod adapted to inipinge against the extension, a tension spring located in the piston-chamber, and a tube conneeting;` the triple-valve with the intermediate chamber in the easing; whereby the cheek- Valve obstructs the passage back from the brake cylinder and holds the brakes in applied position until the auxiliary reservoir has been recharged to the proper pressure; substantially as described.

WILLIAM KEYWOOD.

Witnesses:

A. A. KNIGHT, T. A. WHEELWRIGHT. 

